Page:Popular Science Monthly Volume 20.djvu/586

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570
THE POPULAR SCIENCE MONTHLY.

the electric light at night. Some plants, which were taken into the conservatory a few days before the electric apparatus was put in operation, suffered badly from the deficiency of light—much more than the experimenter had anticipated they would. The plants that were constantly exposed to the electric light became marked with spots, and began in the course of eight days to give evidence of having received serious injuries. That the spots were caused immemediately by the light and not by the disengagement of nitrous vapors, was shown by the fact that only the leaves and parts of leaves that were exposed directly to the light were touched. This satisfied M. Déhérain that the electric light contains rays that are detrimental to plant-life; and the facts indicate that these rays are the violet ones. A direct trial of the capacity of the electric light to decompose carbonic acid was made, with the result that less gas was evolved from plants continuously exposed within twelve feet of the light for several days than is given out in an hour in the sunlight. Plants that enjoyed the light of the conservatory by day and received the electric light at night, suffered less, but were not healthy. The electric light was inclosed in globes of transparent glass and a new set of experiments was instituted with new plants. The mischievous effects of the violet rays were no longer perceived, but the light was not capable of maintaining a healthy growth. The plants started well, but sent out long, thin shoots, which withered and died. Nothing but barley reached a condition near maturity. None of the plants would bloom; but some of them died at the top and took a new start from the root—to wither and die again. Continued experiments showed that these results were due to the lack of power in the electric light to promote the activity of evaporation required to bring the plants to maturity. The plants that were kept in the weakened, diffused light of the conservatory by day, and in the dark at night, fell into a gradual decay. Those that spent the day in the shade out-of-doors, and the night under the electric light, did better, but not much better, than they would have done if they had been left undisturbed out-of-doors. M. Déhérain concludes that the electric light has sufficient power to keep plants alive that would die in the dark, and that it exerts enough positive influence upon vegetation to account for the seemingly favorable results of M. Siemens's experiments, in which vigorous plants that had the light of day, and would have done well anyhow, were made to do better by being given also the electric light at night.

 

Word-Blindness.—M. Magnan, in a communication to the Société de Biologie, has related two cases of aphasia complicated with a special phenomenon, to which he has given the name of word-blindness. One case was that of a man who was seized with a right hemiplegia and aphasia after a fall. A month afterward, the patient recovered the power of speech, little by little: he understood spoken language; he wrote, of his own accord or from dictation, but was incapable of reading either print or manuscript, even when the latter had been written by himself; and he could not name letters written upon a board. The second patient presented similar symptoms. He recognized objects which were shown him, but could not name them; could write words thought or heard, but could not comprehend what was written. He had lost the notion of the value of gesticulations. A similar case is reported by M. Brunardel, in which a post-mortem examination revealed a disordered condition adjoining the pli courbe. The pathology of the affection is explained by supposing that the communications between the psychic visual center, which is situated about the pli courbé, and the convolutions of Broca, are interrupted. In such a case, the patient can still see, speak, and hear, but can not acquire any new idea through his eyes. "Brain" suggests that since no disease of the eye exists, and the affection is owing to a purely psychic phenomenon, it might be better described as "cerebral word-blindness."

 

Death of Dr. J. B. Davis.—Dr. Joseph Barnard Davis, an eminent British authority on skulls, died in May last, at about eighty years of age. He made a voyage to the Arctic regions as surgeon to a whaling ship in 1820, while still a medical student, then settled down in the potteries of Staf-